Electronic device with five surfaces light emitting units and passivation layer covering light emitting units and substrate

ABSTRACT

An electronic device including a driving circuit substrate, a plurality of light emitting units, and a first passivation layer is provided. The driving circuit substrate includes a plurality of active elements. The light emitting units are disposed on the driving circuit substrate and electrically connected to the driving circuit substrate, and each of the plurality of light emitting units is five surfaces light emitting type. The first passivation layer covers the light emitting units and the driving circuit substrate for protecting the light emitting units. One of the active elements provides a current to a corresponding one of the light emitting units, such that lighting efficiency of the corresponding one of the light emitting units is ranged from 70% to 100%. The current includes a plurality of pulse currents spaced apart from each other, and time widths of the pulse currents are the same.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 16/533,718 filed Aug. 6, 2019 which claims thebenefit of U.S. Provisional Application Ser. No. 62/717,000, filed Aug.10, 2018, the benefit of Chinese Patent Application Serial No.201910044000.4, filed Jan. 17, 2019 and the benefit of Chinese PatentApplication Serial No. 201910708175.0, filed Aug. 1, 2019, the entirecontents of which are incorporated herein by reference.

BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure

The present disclosure relates to an electronic device, especially to anelectronic device with a plurality of light emitting units.

2. Description of the Prior Art

Because light-emitting diodes have advantages like small volume, highefficiency, low power consumption, long lifetime, fast switching, highcolor rendering and containing no mercury which is harmful to theenvironment, it is widely used in lighting systems and display devicesin our daily life. Lighting efficiency of normal light-emitting diodeswould be different under different operating current. In applications ofthe present display devices, for reducing the cost, light-emittingdiodes would be designed to be operated at a higher current to generategreater light emitting luminance of a single light-emitting diode and togain the best luminance under the cost with fewer light-emitting diodes.However, when the light-emitting diodes controlled by the activeelements are applied as the backlight of the liquid crystal displaydevices, more light-emitting diodes are operated at higher current,thereby causing energy waste of driving the light-emitting diodes.

SUMMARY OF THE DISCLOSURE

According to an embodiment, the present disclosure provides anelectronic device including a driving circuit substrate, a plurality oflight emitting units, and a first passivation layer. The driving circuitsubstrate includes a plurality of active elements. The light emittingunits are disposed on the driving circuit substrate and electricallyconnected to the driving circuit substrate, and each of the plurality oflight emitting units is five surfaces light emitting type. The firstpassivation layer covers the light emitting units and the drivingcircuit substrate for protecting the light emitting units. One of theactive elements provides a current to a corresponding one of the lightemitting units, such that lighting efficiency of the corresponding oneof the light emitting units is ranged from 70% to 100%. The currentincludes a plurality of pulse currents spaced apart from each other, andtime widths of the pulse currents are the same.

These and other objectives of the present disclosure will no doubtbecome obvious to those of ordinary skill in the art after reading thefollowing detailed description of the embodiment that is illustrated inthe various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a cross-sectional view of an electronicdevice according to a first embodiment of the present disclosure.

FIG. 2 schematically illustrates a cross-sectional view of a drivingcircuit substrate according to an embodiment of the present disclosure.

FIG. 3 schematically illustrates a relation between lighting efficiencyof the light emitting unit generating different colors of light and theoperating current and a relation between the operating current of thelight emitting unit and the luminous intensity.

FIG. 4 schematically illustrates a cross-sectional view of an electronicdevice according to a variant embodiment of the first embodiment of thepresent disclosure.

FIG. 5 schematically illustrates a cross-sectional view of an electronicdevice according to a second embodiment of the present disclosure.

FIG. 6 schematically illustrates a timing of the operating current ofthe light emitting unit according to a second embodiment of the presentdisclosure.

FIG. 7 schematically illustrates a cross-sectional view of an electronicdevice according to a first variant embodiment of the second embodimentof the present disclosure.

FIG. 8 schematically illustrates a cross-sectional view of an electronicdevice according to a second variant embodiment of the second embodimentof the present disclosure.

FIG. 9 schematically illustrates a cross-sectional view of an electronicdevice according to a third variant embodiment of the second embodimentof the present disclosure.

FIG. 10 schematically illustrates a cross-sectional view of anelectronic device according to a fourth variant embodiment of the secondembodiment of the present disclosure.

FIG. 11 schematically illustrates a cross-sectional view of anelectronic device according to a fifth variant embodiment of the secondembodiment of the present disclosure.

DETAILED DESCRIPTION

The present disclosure may be understood by reference to the followingdetailed description, taken in conjunction with the drawings asdescribed below. It is noted that, for purposes of illustrative clarityand being easily understood by the readers, various drawings of thisdisclosure show a portion of the electronic device, and certain elementsin various drawings may not be drawn to scale. In addition, the numberand dimension of each element shown in drawings are for illustrative andare not intended to limit the scope of the present disclosure.

Certain terms are used throughout the description and following claimsto refer to particular elements. As one skilled in the art willunderstand, electronic equipment manufacturers may refer to an elementby different names. This document does not intend to distinguish betweenelements that differ in name but not function. In the followingdescription and in the claims, the terms “include”, “comprise” and“have” are used in an open-ended fashion, and thus should be interpretedto mean “include, but not limited to . . . ”. It will also be understoodthat when an element is referred to as being “coupled to” anotherelement (or other variant), it can be directly connected to the otherelement or indirectly connected (for example, electrically connected) tothe other element through one or more elements.

It should be noted that the technical features in different embodimentsdescribed in the following can be replaced, recombined, or mixed withone another to constitute another embodiment without departing from thespirit of the present disclosure.

Refer to FIG. 1 , which schematically illustrates a cross-sectional viewof an electronic device according to a first embodiment of the presentdisclosure. The electronic device 100 includes a driving circuitsubstrate 102 and a plurality of light emitting units 104, wherein thelight emitting units 104 are disposed on the driving circuit substrate102. The driving circuit substrate 102 includes a plurality of activeelements 106 which are electrically connected to the corresponding lightemitting units 104 for providing currents to the corresponding lightemitting units 104, such that the light emitting units 104 generate thecorresponding light.

FIG. 2 schematically illustrates a cross-sectional view of a drivingcircuit substrate according to an embodiment of the present disclosure.Specifically, the driving circuit substrate 102 may further includes asubstrate 108, and the active elements 106 are formed on the substrate108. For example, the substrate 108 may include flexible substratematerials or rigid substrate materials, for example, polyimide (PI),polyethylene terephthalate (PET), polycarbonate (PC), polyethersulfone(PES), polybutylene terephthalate (PBT), poly(ethylene naphthalate)(PEN), polyarylate (PAR), acrylic, glass, quartz, sapphire, othersuitable materials or combination of the above-mentioned materials, butnot limited thereto.

As shown in FIG. 2 , the driving circuit substrate 102 of thisembodiment may for example be a thin film transistor substrate, and theactive element 106 may for example include thin film transistor. Forexample, each of the light emitting units 104 is provided with currentsby the corresponding thin film transistor. In some embodiments, thinfilm transistors may be arranged in an array on the substrate 108 andare electrically connected to driving elements or control elements bywires, for example, electrically connected to a plurality of power wiresby a plurality of data lines and a plurality of scan lines, but notlimited thereto. In some embodiments, at least one of the activeelements 106 may include at least one thin film transistor. For example,the at least one of the active elements 106 may include a switch thinfilm transistor and a driving thin film transistor, wherein the switchthin film transistor is used to switch on and off statuses of thedriving thin film transistor, the driving thin film transistorelectrically connects the power wire to the corresponding light emittingunit for providing currents to the corresponding light emitting unit,but the present disclosure is not limited thereto. In some embodiments,the driving circuit substrate 102 may include two electrodes 110disposed on its surface and used for being electrically connected to oneof the light emitting units 104, wherein one of the electrodes 110 maybe electrically connected to the corresponding thin film transistor, andthe other one of the electrodes 110 may be electrically connected to acommon voltage source or be grounded. In some embodiments, the thin filmtransistors may include gate electrode G, gate insulting layer GI,semiconductor layer SE, source electrode S and drain electrode D. Thethin film transistor of the present disclosure is not limited to thedrawing shown in FIG. 2 and may also be another kind of thin filmtransistor.

As shown in FIG. 1 , in some embodiments, one of the light emittingunits 104 may for example be a light emitting diode, but not limitedthereto. In some embodiments, the light emitting diode may for examplebe a mini light emitting diode (mini LED) chip, micro light emittingdiode (micro LED) chip, organic light emitting diode (OLED), quantum dotlight emitting diode (QLED), other kinds of light emitting diode orcombinations of the above-mentioned, but not limited thereto. Lightemitting diode may for example be single surface (top surface) lightemitting type, four surfaces (four side surfaces) light emitting type orfive surfaces (top surface and four side surfaces) light emitting type.

As shown in FIG. 1 , in some embodiments, the electronic device 100 mayinclude a plurality of packages 112, and at least one of the lightemitting units 104 is disposed in a corresponding one of the packages112. Each of the packages 112 includes a carrier substrate 114 and anencapsulation layer 116, wherein the light emitting units 104 aredisposed on the carrier substrate 114, and the encapsulation layer 116is used for sealing the light emitting units 104 on the carriersubstrate 114. For example, at least three of the light emitting units104, such as a first light emitting unit 104 a, a second light emittingunit 104 b and a third light emitting unit 104 c, may be disposed ineach of the packages 112, and the first light emitting unit 104 a, thesecond light emitting unit 104 b and the third light emitting unit 104 care used for generating three different colors of light capable of beingmixed into a white light, for example, may respectively include redlight emitting diode, green light emitting diode and blue light emittingdiode, but not limited thereto. Under such condition, each of thepackages 112 may include a plurality of pins 118, wherein the pins 118are electrically connected to the active elements 106 respectively, soeach of the active elements 106 may individually provide a current tothe corresponding light emitting unit 104, and one of the pins 118 isregarded as a common cathode/common anode pin of the first lightemitting unit 104 a, second light emitting unit 104 b and third lightemitting unit 104 c. For example, the active elements 106 may include afirst active element 106 a, a second active element 106 b and a thirdactive element 106 c providing corresponding currents to the first lightemitting unit 104 a, the second light emitting unit 104 b and the thirdlight emitting unit 104 c respectively. In some embodiments, theencapsulation layer 116 may for example include epoxy resin or silicone.In some embodiments, the carrier substrate 114 may for example be ametal lead frame. In some embodiments, the carrier substrate 114 mayalso for example be a semiconductor substrate, and the carrier substrate114 may include an electrostatic discharge protection device or adriving circuit for increasing driving efficiency or having extrafunctions. In some embodiments, the electrostatic discharge protectiondevice may for example be a Zener diode. In some embodiments, thesemiconductor substrate may for example include silicon wafer, galliumarsenide, indium gallium arsenide, indium phosphide, gallium nitride orsilicon carbide, but not limited thereto.

Refer to FIG. 3 and FIG. 1 together. FIG. 3 schematically illustratesrelations between lighting efficiencies and the operating currents ofthe light emitting units generating different colors of light and arelation between the operating current and the luminous intensity of thelight emitting units, wherein the curve C1 represents the relationbetween lighting efficiency and the operating current of one of thelight emitting units 104 generating one color of light, the curve C2represents the relation between lighting efficiency and the operatingcurrent of another one of the light emitting units 104 generatinganother color of light, the curve C3 represents the relation between theoperating current and the luminous intensity of the light emitting units104. For example, the curve C1 may represent the relation between thelighting efficiency and the operating current of a blue light-emittingdiode (the third light emitting unit 104 c), the curve C2 may representthe relation between the lighting efficiency and the operating currentof a red light-emitting diode (the first light emitting unit 104 a). Insome embodiments, the curve C1 may also represent the relation betweenthe lighting efficiency and the operating current of a greenlight-emitting diode (the second light emitting unit 104 b). In FIG. 3 ,the lighting efficiency of the light emitting unit 104 is a normalizedvalue, that is, the peak value of the lighting efficiency is divided byitself and normalized to 1. In this embodiment, for one of the lightemitting units 104 (the second light emitting unit 104 b or the thirdlight emitting unit 104 c) of the curve C1, one of the active elements106 provides a current to the corresponding light emitting unit 104,such that the operating current (that is, the current provided by theactive element 106) of the corresponding light emitting unit 104 islocated in a range R1, and the lighting efficiency of the correspondinglight emitting unit 104 may be ranged from 70% to 100%, in which a peakvalue PK1 of the curve C1 represents a highest lighting efficiency ofthe second light emitting unit 104 b or a highest lighting efficiency ofthe third light emitting unit 104 c when one of the active elements 106provides a third current value I3 to the second light emitting unit 104b or the third light emitting unit 104 c. For example, range R1 maystart from a first current value I1 to a second current value I2. Foranother one of the light emitting units 104 (the first light emittingunit 104 a) of the curve C2, another one of the active elements 106provides another current to the corresponding light emitting unit 104,such that the operating current (that is, another current provided bythe another active element 106) of the light emitting unit 104 islocated in another range R2, and the lighting efficiency of the lightemitting unit 104 may be ranged from 70% to 100%, in which a peak valuePK2 of the curve C2 represents a highest lighting efficiency of thefirst light emitting unit 104 a when one of the active elements 106provides a fourth current value I4 to the first light emitting unit 104a. For example, the range R2 may be greater than the first current valueI1. In some embodiments, the operating current (that is, the currentprovided by the active element 106 to the first light emitting units 104a) of the first light emitting units 104 a may be different from theoperating current (that is, the current provided by another one of theactive elements 106 to the second light emitting units 104 b) of thesecond light emitting units 104 b or the operating current (that is, thecurrent provided by further one of the active elements 106 to the thirdlight emitting units 104 c) of the third light emitting units 104 c.

In this embodiment, the current provided by each of the active elements106 to the corresponding light emitting unit 104 is located in the rangeR1 or the range R2, such that the lighting efficiency of thecorresponding light emitting unit 104 is ranged from 70% to 100%,thereby lowering power consumption of the corresponding light emittingunit 104. For example, the current provided by one of the activeelements 106 to one of the first light emitting units 104 a may belocated in the range R2, the currents provided by the active elements106 to one of the second light emitting units 104 b and one of the thirdlight emitting units 104 c may be located in the range R1. In theembodiment shown in FIG. 1 , the electronic device 100 may for examplebe a display device and includes a non-self-emissive panel 120 and abacklight module 122. Besides, the driving circuit substrate 102 and thelight emitting units 104 of this embodiment may be included in thebacklight module 122 as the elements for generating backlight, but thepresent disclosure is not limited thereto. The non-self-emissive panel120 is disposed on the light emitting units 104. In some embodiments,the non-self-emissive panel 120 may be a liquid crystal display panel,but not limited thereto. For example, the liquid crystal display panelmay include diffuser plate 120 a, brightness enhancement film 120 b,lower polarizer, liquid crystal panel 120 c (including array substrate,liquid crystal layer and color filter layer) and upper polarizer, butnot limited thereto. In some embodiments, the backlight module 122 mayfor example be a direct-lit backlight module, and the light emittingunits 104 are disposed directly under the non-self-emissive panel 120.In some embodiments, the electronic device 100 may for example be asensing device or an antenna.

It is noted that when the light emitting units 104 are applied in thebacklight module 122, the light emitting units 104 are continuouslybright during the displaying of the display device, that is, light iscontinuously generated. In a light emitting diode of prior art backlightmodule, in order to reach the required luminance of backlight (that is,the luminous intensity shown in FIG. 3 ), the operating current of thelight emitting diode is increased to a value corresponding to a lightingefficiency lower than 70% (for example, a current value corresponding toa starting point O1 of the arrow A1 shown in FIG. 3 ). However, in thisembodiment, by lowering the operating current of one of the lightemitting units 104 (the direction of the arrow A1 shown in FIG. 3 ) tobe in the range corresponding to a lighting efficiency ranged from 70%to 100%, power consumption of the one of the light emitting units 104may be decreased. For example, operating current of each of the lightemitting units 104 in this embodiment may be located in right side ofthe peak value PK1 of the curve C1 (or right side of the peak value PK2of the curve C2) and in the range corresponding to a lighting efficiencyranged from 70% to 100%. Although luminous intensity of a single lightemitting unit 104 is decreased (the curve C3 shown in FIG. 3 ), thenumber of the light emitting units 104 of the electronic device 100 inthis embodiment may be increased and greater than the number of theprior art light emitting diodes, such that the luminance generated byall of the light emitting units 104 may reach the required luminance ofbacklight. In another embodiment, when the number of the light emittingunits in this embodiment is equivalent to or similar to the number ofthe light emitting diodes of the prior art, a size (or a light emittingarea) of each of the light emitting units 104 may be designed to begreater than a size (or a light emitting area) of each of the lightemitting diodes of the prior art, such that the luminance generated byall of the light emitting units 104 may reach the required luminance ofbacklight even if the operating current of each of the light emittingunits 104 is reduced. For example, the number of the light emittingunits 104 in a region with one inch diagonal is greater than or equal to10. That is, in a five-inch display device, the number of the lightemitting units 104 may be greater than or equal to 50, or in asixty-five-inch display device, the number of the light emitting units104 may be greater than or equal to 650. Besides, the light emittingunits 104 of the electronic device 100 in this embodiment may beindividually controlled to emit light or not emit light by thecorresponding active element 106. Thus, the electronic device 100 ofthis embodiment may lower power consumption of driving the lightemitting units 104 or increase contrast when displaying. In anotherembodiment, the backlight module 122 may be equipped with a high dynamicrange (HDR) function of the electronic device 100, such that the lightemitting units 104 may generate different luminance. Further, theelectronic device 100 may be configured to display gray levels of 0 toN, where N is 255 for example. When the electronic device 100 display ahigh gray level, such as the gray level of N/2(128) or more, or the graylevel of N(255), the operating current of one of the light emittingunits 104 may be located on the right side of the peak value PK1 of thecurve C1 or on the right side of the peak value PK2 of the curve C2. Forinstance, in the gray level of N/2(128) or more, or the gray level ofN(255), the operating current of the second light emitting unit 104 b orthe operating current of the third light emitting unit 104 c may begreater than or equal to the third current value I3, or the operatingcurrent of the first light emitting unit 104 a may be greater than orequal to the fourth current value I4. As an example, the backlightmodule 122 may set up the operating current to be located on the leftside of the peak value PK1 of the curve C1 or the peak value PK2 of thecurve C2 (that is less than or equal to the third current value I3 orthe fourth current value I4) or on the right side of the peak value PK1of the curve C1 or the peak value PK2 of the curve C2 (that is greaterthan or equal to the third current value I3 or the fourth current valueI4). It is noted that in the present disclosure, the gray levels arereferred to as the gray levels defined by the electronic device 100based on different luminance, and the operating currents of one of thelight emitting unit are for driving the light emitting unit to havedifferent luminance.

FIG. 4 schematically illustrates a cross-sectional view of an electronicdevice according to a variant embodiment of the first embodiment of thepresent disclosure. In the display device 200 of this variantembodiment, one of the light emitting units 204 disposed in each of thepackages 212 may generate a first color light. For example, the lightemitting unit 204 may include at least one light emitting diode, inother words, a single light emitting diode may be disposed in each ofthe packages 212, or a plurality of light emitting diodes generating thesame first color light may be disposed in each of the packages 212.Besides, an encapsulation layer 216 may include a plurality of lightconverting particles for converting the first color light into a secondcolor light. For example, one of the light emitting units 204 may forexample include a blue light emitting diode, and the light convertingparticles 224 may for example include the material capable of convertinga blue light into a white light or a light with other colors, such asfluorescent material, phosphorescent material and quantum dot material,but not limited thereto. Under such condition, each of the packages 212may include two pins 118, one of the pins 118 is electrically connectedto an active element 106, and the other one of the pins 118 is regardedas common cathode/common anode pin. In some embodiments, the carriersubstrate 114 may for example be a metal lead frame. In someembodiments, the carrier substrate 114 may also for example be asemiconductor substrate, and the substrate may include an electrostaticdischarge protection device or a driving circuit for increasing drivingefficiency or having extra functions. In some embodiments, electrostaticdischarge protection device may for example be a Zener diode. In someembodiments, the semiconductor substrate may for example include siliconwafer, gallium arsenide, indium gallium arsenide, indium phosphide,gallium nitride or silicon carbide, but not limited thereto.

The electronic device of the present disclosure is not limited to theabove-mentioned embodiment and may have different variant embodiments orother embodiments. To simplify the description, the same component inother embodiments would be labeled with the same symbol in the firstembodiment. To compare the dissimilarities among the first embodimentand other embodiments conveniently, the following description willdetail the dissimilarities among the first embodiment and otherembodiments and the identical features will not be redundantlydescribed.

Refer to FIG. 5 , which schematically illustrates a cross-sectional viewof an electronic device according to a second embodiment of the presentdisclosure. In the electronic device 300 of this embodiment, theelectronic device 300 may for example be a display device, and the lightemitting units 304 may be regarded as display units, such as pixels orsub pixels, but not limited thereto. In this embodiment, light emittingunits 304 may form a plurality of pixels PX, each of the pixels PXincludes at least three of the lighting units 304. In some embodiments,the electronic device 300 may for example be a sensing device or anantenna. Compared to the embodiment shown in FIG. 1 and FIG. 3 , theelectronic device 300 of this embodiment may include self-emissivepanel. In this embodiment, the light emitting units 304 may include aplurality of first light emitting units 304 a, a plurality of secondlight emitting units 304 b and a plurality of third light emitting units304 c, each of the first light emitting units 304 a, each of the secondlight emitting units 304 b and each of the third light emitting units304 c are used for generating three different colors of light capable ofbeing mixed into a white light and are regarded as sub pixels fordifferent colors. For example, the current provided by the first activeelement 106 a to the first light emitting unit 304 a may be located inthe range R2, the current provided by the second active element 106 b tothe second light emitting unit 304 b and the current provided by thethird active element 106 c to the third light emitting unit 304 c may belocated in the range R1, such that lighting efficiency of each of thelight emitting units 304 may be ranged from 70% to 100%, therebylowering power consumption of the light emitting units 304.

Refer to FIG. 6 as well as FIG. 3 and FIG. 5 . FIG. 6 schematicallyillustrates a timing of the operating current of the light emitting unitaccording to a second embodiment of the present disclosure, wherein afirst signal S1 represents the operating current provided to one of thelight emitting units which is regarded as one of the sub pixels of aprior art display device, a second signal S2 represents the operatingcurrent provided to one of the light emitting units 304 which isregarded as one of the sub pixels of the electronic device 300 of thesecond embodiment. It is noted that when the light emitting units 304are regarded as sub pixels, the light emitting units 304 are notcontinuously bright during displaying of the display device and stillneed to show the luminance of gray level of the sub pixels. In the priorart light emitting units which are regarded as sub pixels, in order toshow different gray levels, the operating current provided to the lightemitting units is lower than the current value IO which correspond tothe lighting efficiency lower than 70% (for example, the current valuecorresponding to the starting point O2 in the arrow A2 shown in FIG. 3), and as the first signal S1 shown in FIG. 6 , in a single frame timeFT, the light emitting units are continuously provided with thisoperating current IO, such that lighting efficiency of the lightemitting units are poor. However, in this embodiment, the operatingcurrent provided to the light emitting units 304 may be increased andgreater than or equal to the current value IP which correspond to alighting efficiency larger than or equal to 70% (the direction of thearrow A2 shown in FIG. 3 ), thereby increasing lighting efficiency ofthe light emitting units 304. For example, the operating current of eachof the light emitting units 304 in this embodiment may be located inleft side of the peak value PK1 of the curve C1 (or left side of thepeak value PK2 of the curve C2) and in the range which corresponds tothe lighting efficiency ranged from 70% to 100%. In another embodiment,for displaying a higher gray level, such as gray level of N/2(128) ormore or gray level of N(255), the operating current of the first lightemitting unit 304 a may be located at the right side of the peak valuePK2 of the curve C2 (i.e. greater than or equal to the fourth currentvalue I4), and the operating current of the second light emitting unit304 b or the operating current of the third light emitting unit 304 cmay be located at the right side of the peak value PK1 of the curve C1(i.e. greater than or equal to the third current value I3). Furthermore,taking the lighting efficiencies and white balance of the first lightemitting unit 304 a, the second light emitting unit 304 b and the thirdlight emitting unit 304 c into account, the present disclosure is notlimited that which one of the first light emitting unit 304 a, thesecond light emitting unit 304 b and the third light emitting unit 304 cis provided with the operating current located at the right side of thepeak value PK1 of the curve C1 or the peak value PK2 of the curve C2while the display device displays the gray level of N/2(128) or more orthe gray level of N(255). In a further embodiment, for displaying alower gray level, such as less than N/2, e.g. the gray level of 50 orless, the gray level of 10, or the gray level of 1, the operatingcurrent of the first light emitting unit 304 a may be located at theleft side of the peak value PK2 of the curve C2 (i.e. less than or equalto the fourth current value I4), and the operating current of the secondlight emitting unit 304 b or the operating current of the third lightemitting unit 304 c may be located at the left side of the peak valuePK1 of the curve C1 (i.e. less than or equal to the third current valueI3). In a yet another embodiment, for displaying a higher gray level,such as the gray level of N/2(128) or more or gray level of N(255), theoperating current of the light emitting unit 304 is located at the rightside of the peak value PK1 or PK2 of the curve C1 or C2, and fordisplaying a lower gray level, such as the gray level of 50 or less, orthe gray level of 10, the operating current of the light emitting unit304 is located at the left side of the peak value PK1 of the curve C1 orthe peak value PK2 of the curve C2. In other words, the operatingcurrent of one of the light emitting units 304 in this embodiment can beset to be located at the left side or the right side of the peak valuePK1 or PK2 of the curve C1 or C2 according to the gray level desired tobe displayed. In a further another embodiment, the operating currents ofa part of the light emitting units 304 are located at the left side ofthe peak value PK1 of the curve C1 or the peak value PK2 of the curve C2when the display device displays different gray levels, and theoperating currents of another part of the light emitting units 304 arelocated at the left side or the right side of the peak value PK1 or PK2of the curve C1 or C2 based on different gray levels when the displaydevice displays the different gray levels. In order to avoid over highluminance caused by increasing the current value, the current providedby the active element 106 to the light emitting unit 304 in the singleframe time FT is not a fixed value in this embodiment, but includes aplurality of pulse current P spaced apart from each other, as shown insecond signal S2 in FIG. 6 , the current value IP of each of the pulsecurrents P is located in the range of the operating current in the lightemitting unit 304 which correspond to the lighting efficiency rangedfrom 70% to 100% (the range R1 of the curve C1 or the range R2 of thecurve C2 shown in FIG. 3 ). By adjusting the time width W of each of thepulse currents P, the luminance of one the light emitting units 304 inthe single frame time FT meets the required luminance. For example, whena gray level with higher luminance is required, time width W of each ofthe pulse currents P may be increased; and when a gray level with lowerluminance is required, time width W of each of the pulse currents P maybe decreased. In some embodiments, time width W of different pulsecurrents P may be different. It is noted that the previous descriptionrelated to the operating currents may be applied to an embodiment of thelight emitting units 304 including one kind of light emitting diode,such as blue light emitting diode, or another embodiment of the lightemitting units 304 including two kinds of the light emitting diodes,such as blue light emitting diode and the green light emitting diode. Inthe embodiment of the light emitting units 304 including one kind oflight emitting diode, such as the blue light emitting diode, the bluelight generated from the blue light emitting diode may be combined withdifferent light converting particles for converting the blue light intogreen light or red light. In the another embodiment of the lightemitting units 304 including two kinds of the light emitting diodes,such as the blue light emitting diode and the green light emittingdiode, the blue light generated from the blue light emitting diode maybe combined with the light converting particles for converting the bluelight into red light.

The embodiment of the light emitting unit including one kind of lightemitting diode is taken as an example for further detailed description.FIG. 7 schematically illustrates a cross-sectional view of an electronicdevice according to a first variant embodiment of the second embodimentof the present disclosure. As shown in FIG. 7 , the electronic device350 provided by this variant embodiment is different from the electronicdevice 300 shown in FIG. 5 in that the light emitting units 354 of theelectronic device 350 include light emitting diodes for generating asame first color of light, and the electronic device 350 may furtherinclude a light converting layer 384 disposed on the corresponding lightemitting unit 354 and used for converting the light generated by thecorresponding light emitting unit 354 into light with desired color. Inthis embodiment, the color of light generated by the light emitting unit354 serving as a color of one sub-pixel SPX and a pixel PX includingthree light emitting units 354 are taken as an example, but the presentdisclosure is not limited thereto. In this embodiment, the lightconverting layer 384 may include a first light converting layer 384 aand a second light converting layer 384 b, in which the first lightconverting layer 384 a is disposed on one light emitting unit 354 andused for converting the first color of light into a second color oflight, the second converting layer 384 b is disposed on another onelight emitting unit 354 and used for converting the first color of lightinto a third color of light, and another light emitting unit 354 has nolight converting layer 384 disposed thereon. Accordingly, the firstcolor of light, the second color of light and the third color of lightmay be mixed into white light.

Specifically, the electronic device 350 may include a pixel defininglayer 386 disposed on the substrate 102, and the pixel defining layer386 has a plurality of openings 386 a, in which at least one lightemitting unit 354 is disposed in each opening 386 a. Furthermore, theelectronic device 350 of this embodiment may further include anothersubstrate 388, a light shielding layer 390 and a light scattering layer394. The substrate 388 and the substrate 102 are disposed opposite toeach other, and the light shielding layer 390 is formed on the substrate388 and includes a plurality of opening 390 a. In this embodiment, theopenings 390 a of the light shielding layer 390 correspond to theopenings 386 a of the pixel defining layer 386 respectively, such thatlight emitted out from each opening 390 a to the substrate 388 may beregarded as light of one sub-pixel SPX. The light shielding layer 390may include light shielding material, such as black photoresistmaterial. A partition wall 392 may be disposed on the light shieldinglayer 390 and may also have a plurality of openings 392 a, and eachopening 392 a corresponds to one of the opening 390 a of the lightshielding layer 390. The partition wall 392 may further include lightblocking material, such as white photoresist material for reflectinglight. The first light converting layer 384 a, the second lightconverting layer 384 b and the light scattering layer 394 arerespectively formed and disposed in a corresponding one of the openings384 a. In this embodiment, the electronic device 350 may optionallyfurther include a first color filter layer 396 a, a second color filterlayer 396 b and a third color filter layer 396 c for absorbing lightwith different colors. Each of the first color filter layer 396 a, thesecond color filter layer 396 b and the third color filter layer 396 cis disposed in a corresponding one of the openings 390 a and on acorresponding one of the first light converting layer 384 a, the secondlight converting layer 384 b and the light scattering layer 394. Forexample, the first color filter layer 396 a, the second color filterlayer 396 b and the third color filter layer 396 c may be a red colorfilter, a green color filter and a blue color filter respectively, butnot limited thereto. In another embodiment, the first color filter layer396 a or the second color filter layer 396 b may be a yellow colorfilter layer. In another embodiment, the first color filter layer 396 aor the second color filter layer 396 b may be replaced by a distributedbragg reflector. In another embodiment, the electronic device 350 mayinclude a low refractive layer between the first color filter layer 396a and the first light converting layer 384 a or between the second colorfilter layer 396 b and the second light converting layer 384 b. Therefractive index of the low refractive layer is less than the refractiveindex of the color filter layer 396 a, 396 b and the light convertinglayer 384 a, 384 b. After each of the substrate 102 and the substrate388 has the elements formed thereon, the substrate 102 and the substrate388 may be adhered to each other by an adhesive layer 398, in which thelight emitting units 354, the pixel defining layer 386, the lightshielding layer 390, the partition wall 392, the light scattering layer394 and the color filter layers are disposed between the substrate 102and the substrate 388. The adhesive layer 398 may include for exampleoptical clear adhesive (OCA) or optical clear resin (OCR), but notlimited thereto. The electronic device 350 of this embodiment is aso-called two-substrate type self-luminous display device, but notlimited thereto.

In some embodiments, the electronic device 350 may also be aone-substrate type self-luminous display device. In other words, thelight shielding layer 390 and the partition wall 392 may be formed onthe pixel defining layer 386, each of the light converting layers 384and the light scattering layer 394 may be formed on the correspondingone of the light emitting units 354 respectively, and the color filterlayers are respectively formed on the light converting layers 384 andthe light scattering layer 394. Furthermore, an encapsulation layer maybe formed to cover the light shielding layer 390 and the color filterlayers. In some embodiments, the color of light generated from the lightemitting units 354 may be different from the colors of the sub-pixels,for example the light generated from the light emitting units 354 may beultraviolet or blue light, and in such situation, the light scatteringlayer 394 may be replaced with the light converting layer that cangenerate light with a color the same as the color of one sub-pixel SPX.

FIG. 8 schematically illustrates a cross-sectional view of an electronicdevice according to a second variant embodiment of the second embodimentof the present disclosure. As shown in FIG. 8 , the difference betweenthe electronic device 400 provided by this variant embodiment and theelectronic device 300 shown in FIG. 5 is that the light emitting units404 are directly disposed on the driving circuit substrate 102. In someembodiments, the electronic device 400 may further include a firstpassivation layer 426 covering the light emitting units 404 and thedriving circuit substrate 102 for protecting the light emitting units404. Because the first passivation layer 426 directly covers the lightoutput surface of the light emitting units 404, for lowering theinfluence of the first passivation layer 426 to the luminance of outputlight of the light emitting units 404, the first passivation layer 426with 1 micrometer thickness has a transmittance greater than or equal to63%, or the first passivation layer 426 with 1 micrometer thickness hasan optical density (OD) less than or equal to 0.2. For example,thickness T1 of the first passivation layer 426 directly on one of thelight emitting units 404 may be ranged from 1 micrometer to 5micrometers.

In some embodiments, in addition to the function of protecting the lightemitting units 404, the first passivation layer 426 may also have thefunction of lowering visibility of the light emitting units 404. Forexample, the first passivation layer 426 with 1 micrometer thicknessfurther has a transmittance less than or equal to 98%. In someembodiments, the first passivation layer 426 may for example includephotoresist material, silicone or epoxy resin. In some embodiments, thefirst passivation layer 426 may further include light absorbingmaterial, light scattering particles or combinations thereof. The lightabsorbing material may for example include titanium oxide (TiO₂),zirconium oxide (ZrO₂), aluminum oxide (A1 ₂O₃), indium oxide (In₂O₃),zinc oxide (ZnO), tin oxide (SnO₂), antimony trioxide (Sb₂O₃), siliconoxide (SiO₂) or combinations thereof, but not limited thereto. The lightscattering particle may for example include Au, Ag, Cu, Pt, Fe, Co, Ni,Mn or combinations thereof, but not limited thereto.

In some embodiments, in order to increase light mixing of adjacent twoof the light emitting units 404 in the same pixel PX or decrease lightmixing of adjacent two of pixels PX, a space T3 between adjacent two ofthe pixels PX may be greater than a space T2 between adjacent two of thelight emitting units 404 in the same pixel PX. In some embodiments, thethickness T1 of the first passivation layer 426 directly on one of thelight emitting units 404 may be less than or equal to the space T2between adjacent two of the light emitting units 404 in the same pixelPX. In some embodiments, the space T3 between adjacent two of the pixelsPX may be larger than the thickness T1 of the first passivation layer426 directly on one of the light emitting units 404. For example, thespace T2 may be ranged from 3 micrometers to 20 micrometers, and thespace T3 may larger than about 20 micrometers.

In this embodiment, the first passivation layer 426 may further cover apart of the driving circuit substrate 102. In order to cover the wires(for example the metal wires) in the driving circuit substrate 102, thefirst passivation layer 426 directly on the part of the driving circuitsubstrate 102 without light emitting units 404 disposed thereon may havea thickness T4. For example, when one of the light emitting units 404 isa micro light emitting diode, thickness T4 may be ranged from 4micrometers to 15 micrometers. When one of the light emitting units 404is a mini light emitting diode, thickness T4 may be ranged from 50micrometers to 150 micrometers. In some embodiments, thickness T4 may belarger than thickness T1. In some embodiments, the electronic device 400may further include a second passivation layer (the second passivationlayer shown in FIG. 10 ) covering a part of the driving circuitsubstrate 102 without light emitting units 404 disposed thereon, andtransmittance of the second passivation layer may be different fromtransmittance of the first passivation layer 426.

FIG. 9 schematically illustrates a cross-sectional view of an electronicdevice according to a third variant embodiment of the second embodimentof the present disclosure. As shown in FIG. 9 , the difference betweenthe electronic device 500 of this variant embodiment and the electronicdevice 400 shown in FIG. 7 is that the first passivation layer 526includes a plurality of protecting blocks 528 spaced apart from eachother, and each of the protecting blocks 528 covers all of the lightemitting units 404 in the corresponding one of the pixels PX. Becausethe protecting blocks 528 covering different pixels PX are spaced apartfrom each other, when the electronic device 500 is folded, cracks wouldnot be easily generated. In some embodiments, the electronic device 500may further include a second passivation layer (the second passivationlayer shown in FIG. 10 ) covering a part of the driving circuitsubstrate 102 without light emitting units 404, and transmittance of thesecond passivation layer may be different from transmittance of thefirst passivation layer 526.

FIG. 10 schematically illustrates a cross-sectional view of anelectronic device according to a fourth variant embodiment of the secondembodiment of the present disclosure. As shown in FIG. 10 , thedifference between the electronic device 600 of this variant embodimentand the electronic device 400 shown in FIG. 7 is that the firstpassivation layer 626 includes a plurality of protecting blocks 628spaced apart from each other, each of the protecting blocks 628 coversone of the light emitting units 404. Because the protecting blocks 628covering different light emitting units 404 are spaced apart from eachother, when the electronic device 600 is folded, cracks would not beeasily generated. In some embodiments, the electronic device 600 mayfurther include a second passivation layer 630 disposed on a part of thedriving circuit substrate 102 without light emitting units 404 disposedthereon, and transmittance of the second passivation layer 630 may bedifferent from transmittance of the first passivation layer 626, suchthat the disposition of the second passivation layer 630 may adjustvisibility of the wires (for example the metal wires) in the drivingcircuit substrate 102, thereby lowering visibility of the drivingcircuit substrate 102.

FIG. 11 schematically illustrates a cross-sectional view of anelectronic device according to a fifth variant embodiment of the secondembodiment of the present disclosure. As shown in FIG. 11 , thedifference between the electronic device 700 of this variant embodimentand the electronic device 400 shown in FIG. 7 is that the electronicdevice may further include a plurality of third passivation layers 732a, 732 b and 732 c covering the corresponding light emitting elements404 a, 404 b and 404 c respectively. Transmittances of the thirdpassivation layer 732 a, 732 b and 732 c may correspond to the coveredlight emitting units 404 a, 404 b and 404 c respectively, such that thelight generated from the corresponding light emitting units 404 a, 404 band 404 c are allowed to penetrate through. For example, the lightemitting unites 404 a, 404 b and 404 c are used for generating differentcolors of light, wherein the third passivation layer 732 a covers thelight emitting unit 404 a, and the light from light emitting unit 404 aare allowed to penetrate through; the third passivation layer 732 bcovers the light emitting unit 404 b, and the light from light emittingunit 404 b are allowed to penetrate through; and the third passivationlayer 732 c covers the light emitting unit 404 c, and the light fromlight emitting unit 404 c are allowed to penetrate through. In someembodiments, the third passivation layer 732 a, 732 b and 732 c may be acolor filter formed by lithography process or inject process. Under suchcondition, the third passivation layer 732 a, 732 b and 732 c may have aflat upper surface. In some embodiments, the first passivation layer 726may not cover the third passivation layer 732 a, 732 b and 732 c and thelight emitting units 404, that is, an upper surface of the firstpassivation layer 726 may be coplanar with the upper surfaces of thethird passivation layer 732 a, 732 b and 732 c or lower than uppersurfaces of the third passivation layer 732 a, 732 b and 732 c. Thematerial of the first passivation layer 726 may for example be the sameas the first passivation layer shown in FIG. 8 , which will not beredundantly described herein, but not limited thereto. In someembodiments, the first passivation layer 726 may also cover all thelight emitting units 404 as shown in FIG. 8 or include the protectingblocks shown in FIG. 9 or FIG. 10 . In some embodiments, the thirdpassivation layer 732 a, 732 b and 732 c may also include pigment oradhesive and is formed by mixing pigment with adhesive and a dispenseprocess. Under such condition, upper surfaces of the third passivationlayer 732 a, 732 b and 732 c may be convex.

As mentioned above, in the electronic device of the present disclosure,power consumption of the light emitting units may be lowered by makingthe operating current of the light emitting units to be in a range whichcorrespond to a lighting efficiency ranged from 70% to 100%, and bycontrolling emitting of the light emitting units through the activeelements, contrast would be increased when the electronic device isdisplaying.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the disclosure. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. An electronic device, comprising: a drivingcircuit substrate comprising a plurality of active elements; a pluralityof light emitting units disposed on the driving circuit substrate andelectrically connected to the driving circuit substrate, wherein each ofthe plurality of light emitting units is five surfaces light emittingtype; and a first passivation layer covering the plurality of lightemitting units and the driving circuit substrate for protecting theplurality of light emitting units, wherein one of the plurality ofactive elements provides a current to a corresponding one of theplurality of light emitting units, such that lighting efficiency of thecorresponding one of the plurality of light emitting units is rangedfrom 70% to 100%, and wherein the current comprises a plurality of pulsecurrents spaced apart from each other, and time widths of the pluralityof pulse currents are the same.
 2. The electronic device according toclaim 1, wherein a thickness of the first passivation layer directly onone of the plurality of light emitting units is less than or equal to aspace between adjacent two of the plurality of light emitting units. 3.The electronic device of claim 1, wherein the first passivation layerhas a thickness greater than 1 micrometer, and the first passivationlayer has a transmittance greater than or equal to 63%.
 4. Theelectronic device of claim 1, wherein a part of the first passivationlayer directly on a part of the driving circuit substrate without theplurality of light emitting units disposed thereon has a thickness, thepart of the first passivation layer is disposed between adjacent two ofthe plurality of light emitting units, and the thickness of the part ofthe first passivation layer is greater than a thickness of another partof the first passivation layer directly on one of the plurality of lightemitting units.
 5. The electronic device of claim 1, wherein the firstpassivation layer directly on a part of the driving circuit substratewithout the plurality of light emitting units disposed thereon has athickness, and the thickness is ranged from 4 micrometers to 15micrometers.
 6. The electronic device of claim 1, wherein the firstpassivation layer directly on a part of the driving circuit substratewithout the plurality of light emitting units disposed thereon has athickness, and the thickness is ranged from 50 micrometers to 150micrometers.
 7. The electronic device of claim 1, wherein one of theplurality of light emitting units comprises a mini light emitting diodeor a micro light emitting diode.
 8. The electronic device of claim 1,wherein the plurality of light emitting units form a plurality ofpixels, and a space between adjacent two of the plurality of pixels islarger than a thickness of the first passivation layer directly on oneof the plurality of light emitting units.
 9. The electronic device ofclaim 1, wherein the plurality of light emitting units form a pluralityof pixels, and a space between adjacent two of the plurality of pixelsis larger than a space between adjacent two of the plurality of lightemitting units in one of the plurality of pixels.
 10. The electronicdevice of claim 1, further comprising a second passivation layerdisposed on a part of the driving circuit substrate without theplurality of light emitting units, wherein a transmittance of the secondpassivation layer is different from a transmittance of the firstpassivation layer.